Re: [PATCH v3 2/8] hwmon: (pmbus/adm1266) don't clobber GPIO bits before PDIO read in get_multiple

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Uninitialized stack memory use on short I2C block reads
- [High] Missing required locking for PMBus hardware accesses
--

commit feacc189ff4113f817d364f381e4726e168838b1
Author: Abdurrahman Hussain <abdurrahman@nexthop.ai>

hwmon: (pmbus/adm1266) don't clobber GPIO bits before PDIO read in get_multiple

This commit prevents the pdio loop in adm1266_gpio_get_multiple() from
overwriting previously populated gpio bits by dropping a redundant assignment.

> diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm1266.c
> index 11f9a44f4361a..4dd67c02b412e 100644
> --- a/drivers/hwmon/pmbus/adm1266.c
> +++ b/drivers/hwmon/pmbus/adm1266.c
> @@ -210,7 +210,6 @@ static int adm1266_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask
>  
>  	status = read_buf[0] + (read_buf[1] << 8);

i2c_smbus_read_block_data() returns the number of bytes read on success.

If a short read occurs and fewer than two bytes are returned, does this
result in using uninitialized stack data for read_buf[1]?

I note this regression is fixed later in the series by a commit regarding
short block-read responses in the gpio accessors.

Additionally, the hardware monitoring subsystem guidelines require drivers
to implement locking for attributes registered by other means.

Can these unlocked pmbus reads in adm1266_gpio_get_multiple() interleave
with multi-message transactions from other threads, potentially corrupting
the active page state?

I see this regression is also resolved later in the series by a commit
that serializes gpio pmbus accesses with pmbus_lock.

> -	*bits = 0;
>  	for_each_set_bit_from(gpio_nr, mask, ADM1266_GPIO_NR + ADM1266_PDIO_NR) {
>  		if (test_bit(gpio_nr - ADM1266_GPIO_NR, &status))
>  			set_bit(gpio_nr, bits);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260518-adm1266-gpio-fixes-v3-0-e425e4f88139@nexthop.ai?part=2